Beam arrays are device components in a wide variety of optical devices and optical systems. For example, laser beam arrays comprise light sources useful for a range of important applications including optical signal generation, optical sensing and laser pumping. Beam arrays used in these applications include linear beam arrays wherein a plurality of light beams propagate along axes which are substantially confined to a single plane or two dimensional beam arrays wherein light beams have propagation axes which occupy a plurality of planes. The versatility and utility of beam array light sources largely arises from their spatial characteristics and optical properties. Particularly, the order of individual beams in a beam array provides a convenient means of discriminating between light beams corresponding to different optical signals. In addition, the spatial arrangement of light beams in a beam array allows individual light beams to be efficiently optically coupled to a wide variety of selected receiving elements. Furthermore, beam arrays comprise optical sources capable of providing a wide range of radiant powers.
Recent developments in the field of semiconductor laser diodes has resulted in the availability of diode laser bar arrays which provide light sources for a variety of applications in the fields of optical telecommunications, solid state laser pumping and material processing. A diode laser bar array is formed by combining multiple semiconductor diode laser emitters to generate a plurality of diode laser beams. A diode laser consists of a modified p-n junction within a multi-layer semiconductor structure. Lasing action is provided by applying a potential difference across the modified p-n junction. The modified p-n junction is doped and contained within a laser cavity, thus, providing a gain medium for the laser.
Diode laser bar arrays have a number of advantages over conventional optical sources. First, diode laser bar arrays are capable of providing very high radiant powers for a wide variety of lasing wavelengths, routinely providing radiant powers up to about hundreds of Watts. Second, diode laser bar arrays exhibit low power consumption, minimal heat load and long lifetimes. Finally, diode laser bar array light sources are compact, rugged and inexpensive.
Despite the clear benefits of diode laser bar arrays, the full potential of this technology to many optical applications is not currently realized due to several limitations of this technology. First, individual diode laser elements in a laser bar array typically exhibit large beam divergence, which can substantially limit the photon density and brightness of these optical sources. Beam divergence of diode laser elements in a bar array also degrades the efficiency in which these sources can be optically coupled to one or more receiving elements. Second, the pitch of commercially available diode laser bar arrays is substantially limited by the packaging, electronic requirements and cooling schemes of these devices. Limitations on bar array pitch significantly limits the photon densities and brightnesses achievable using laser diode bar array optical sources.
It will be appreciated from the foregoing that a need exists for high power beam array light sources. Particularly, beam array light sources having a selectively adjustable pitch and brightness are needed. Accordingly, it is an object of the present invention to provide methods, devices and device components capable of efficiently controlling the propagation axes of light beams in a beam array. The present invention provides pitch controllers providing selective control over the spacing between adjacent beams in a beam array. In addition, the present invention provides beam array controllers capable of efficiently coupling light beams in a beam array to one or more receiving devices or photosensitive materials. Further, the present invention provides methods and devices for selectively adjusting the brightness and brightness spatial distribution of a beam array, particularly well suited for parallel beam arrays.